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By Henry N. McCarl

[The Construction Materials section contains the following Chapters: Aggregates Cement and Cement Raw Materials Crushed Stone Dimension and Cut Stone Lightweight Aggregates Gypsum and Anhydrite Sand and Gravel Insulating Materials-Thermal and Sound Slag Roofing Granules] Mineral aggregates are those natural and manufactured industrial mineral and rock materials that provide bulk and strength in portland cement concrete, bituminous concrete mixes, and plaster or stucco surfaces. They may also provide special characteristics such as thermal and acoustical insulation, weight, surface textures, abrasion resistance, and impermeability to various concrete products and mixes. Most aggregates are relatively inexpensive materials, but despite their low unit value, the tonnages consumed each year in the United States and throughout the" world make mineral aggregates by far the leading industrial mineral and rock materials both in terms of volume (tonnage) produced and value consumed. The major use of mineral aggregates is in concrete. The low cost, high bulk aggregates tend to keep concrete construction costs at levels competitive with other building materials. Other major uses of aggregates include highway and railroad base or ballast materials, graded fill, and various industrial uses such as metallurgical and chemical fluxes and raw materials-these latter uses are often considered nonaggregate uses of mineral aggregate materials. The per-ton value of mineral aggregate materials at the production plant in 1980 and 1981 varied from $2 to $5 for most sand and gravel and crushed stone, $3 to $6 for air-cooled slag, $7 to $20 for expanded slag and expanded clay or shale aggregate, to as much as $165 to $320 for expanded perlite or vermiculite. The expanded lightweight aggregates have been dramatically affected by increasing fuel costs. It is ironic that the specialized aggregates used as insulating materials to conserve energy cost so much more to produce due to the high proportion of energy consumed in their production. The first four parts of "Construction Materials" deal with the utilization of four major mineral aggregate types: Crushed Stone, Lightweight Aggregates, Sand and Gravel, and Slag. While the focus will be on the use of these industrial minerals and rocks, there will also be some coverage of sources, mining and production, especially in those cases where they are not discussed in the Commodity section of this book.

Jan 1, 1983

By AIME AIME

BORN a Chicagoan, on Aug;. 31, I879. Oscar Johnson lived in that city until young manhood. As a youth delivering newspapers he set his sight on the l university of Chicago and at sixteen years of age he began working summer vacations in the foundry of the Pullman Company. Misfortune came to his family during the summer of 1898 when tuberculosis took his only sister and brother. His mother, apprehensive of Oscar's health, urged him to try the West at least for awhile. So late summer found Oscar in Salt Lake City, employed by the Trent Engineering & Machinery Co. At that time it was busy building equipment for use in the war with Spain. Though he did not know it then, Oscar war was laying the groundwork for his present membership on the Mining Equipment Industry Advisory Committee of the W.P.B., a post which keeps him commuting between Denver and Washington.

Jan 1, 1944

By D. E. Buchanan

The: volatility of a motor fuel is an index to its quality and to the satisfaction that will attend its use as an internal combustion engine fuel. Natural gasoline is concentrated volatility; threfore, it is quite natural that the most important market for natural gasoline should be for blending with less volatile refinery gasolines. Progress in the art of manufacturing natural gasoline, particularly in fractionation, which has made possible the elimination of the fixed gases and lighter hydrocarbons having a tendency to gasify at atmospheric pressure and temperature, has made it possible and desirable for refiners to utilize an ever-increasing percentage of natural gasoline in their finished product. This, in turn, has enabled the industry at large with each succeeding year to supply to the consuming public a better grade of gasoline. While cracking processes and improved fractionation in refinery operation have resulted in higher yields of gasoline per barrel of crude oil refined, natural gasoline has also played a large part in this respect because it has enabled the refiner to cut deeper into the crude and still maintain proper standards of volatility by blending natural gasoline with the product from his stills. There is, of course, with even the present improved grades of natural gasoline, a limit to the percentage that may properly be used. This percentage varies with different grades of crude oil, varies according to the facilities employed at the refinery and varies according to the grade of motor fuel manufactured; therefore it is not possible to say that for a certain predetermined amount of motor fuel to be manufactured in a given area, a certain definite amount of natural gasoline will be required. It is, however, generally conceded, and statistics bear out the statement, that the average gallon of motor fuel sold in this country contains approxi-matcly 11 per cent. of natural gasoline. Isolated cases may be found where in a very few refineries during certain seasons no natural gasoline is used, while in other plants as high as 35 per cent. and 40 per cent, natural gasoline is used in certain grades of motor fuels. Production Statistics The total production of natural gasoline for 1927, including California, is estimated at 1,627,600,000 gal. This represents an increase of 20 per

Jan 1, 1928

By Strathmore R. B. Cooke, Paul B. Queneau

The kinetics of the dissolution of scheelite in basic solutions of carbonate and fluoride were investigated. Work was also done with solutions of alkali metal chloride, hydroxide, phosphate, and mixtures of phosphate and fluoride. The study was conducted at 90 psig and at temperatures ranging from 100" to 155"C, and both natural and synthetic scheelite single crystals were used. The interaction of scheelite with carbonate solutions generally followed a parabolic rate law, and resulted in the formation of calcite crystals on the attached surface. The transport of the CO3 through the calcite to the scheelite surface was probably rate -controlling between 115" and 135°C. Positive deviations from Parabolic behavior were observed at 100" and 155?C, presumably due to the calcite grain growth, and to the formation of a noncoherent calcite layer, respectively. The leaching of scheelite with alkaline fluoride solution produced a calcium fluoride reaction-product which covered the surface as a sheet-like layer. Below 110°C the dissolution rate was parabolic; at 115" and 135°C it was linear. In the linear region, the periphery of the calcium fluoride layer lifted from the sample. Only the lower layers, braced by the scheelite substratum, remained unbroken. This bound layer, approximately constant in thickness, limited the rate at which the fluoride could attack the scheelite. The phosphate and phosphate-fluoride leaches dissolved scheelite at a linear rate; solid reaction products were respectively hydroxyapatite and fluorapatite. Sodium hydroxide and chloride were not effective leachants, and did not produce observable solid reaction products. THE feasibility of pressure leaching of scheelite pulps with basic solutions containing either carbonate or fluoride ions, as indicated by the following equations, has been established by previous investigators:1-3 200°C CaWO4s + CO37q - CaCO3s+WO4aq [1] 200°C CaWO4s + 2Faq ^ CaF2s+WO4aq [2] It is to be noted that a commercial process employing reaction [I] is in use at Union Carbide's operation near Bishop, Calif. In the earlier work referred to, it was apparent that the precipitation of the solid reaction-product on the scheelite particles sharply reduced contact of the leachant with the scheelite. We have extended this work by studying the kinetics of dissolution employing single crystals of scheelite of known exposed surface area. In addition, the effectiveness of solutions of phosphate, of phosphate with fluoride, and of chloride and hydroxide as leachants for scheelite have been investigated. EXPERIMENTAL Apparatus. The low-pressure autoclave used in this wo (100 psig maximum) is essentially that of J. Halpern4 as modified by F. A. Forward.5 Constructed entirely of 316 stainless steel, its maximum capacity is 4000 ml. The temperature in the autoclave was regulated to *0.5?C by a Wheelco thermocouple controller. A 4-in. diam, three-bladed impeller, circulated solution upward against the sample, and a strobo-scope permitted holding the stirring rate to *15 rpm. A check valve and a "pop" type safety valve were installed, a sample holder was fixed to an externally adjustable rod, and a water-cooled condenser was placed in series with the sampling valve. The stainless steel sample holder, Fig. 1, held the epoxy-mounted sample (f) five mm above the impeller. Tightening the tapered sleeve (d) positioned the epoxy-resin specimen-mount by forcing it back against the spacer (c). The mount (e) was 1 in. diam. Sample Description and Preparation. Both synthetic and natural scheelite crystals were leached. The former were single crystals of 99.95 pct purity which were leached approximately perpendicular to the "c" axis; they were supplied by the Gallard-Schlesinger Chemical Manufacturing Corp. The natural crystals, supplied by Minerals Unlimited, were transparent, analyzed 99.8 pct CaWO4, and in ultraviolet illumination exhibited the characteristic blue glow of substantially molybdenum-free scheelite. To permit exposure of an essentially constant surface area of scheelite to the leachant, the samples were mounted in Scotchcast Brand Resin No. 250 (Minnesota Mining and Manufacturing Co.). The mount-

Jan 1, 1970

Plans for the Petroleum Division during the ensuing year are in process of development, in contemplation of the usual fall meetings in the Mid-Continent and California areas, as well as the annual meeting to be held in New York in February, 1936. Houston, Texas has been suggested as the place for the Mid-Continent fall meeting, the exact date to be announced shortly. During the past year, the Division's technical programs, as in former years, have emphasized the wide fields of engineering endeavor in the petroleum industry yet remaining for more thorough investigation and discussion. An effort has been made to bring an international interest into the proceedings of the Division by inviting the participation of prominent foreign technologists. This viewpoint should promote a continuation in 1935 of past high standards, afford a more thorough understanding of problems throughout the membership, and maintain the Institute's position among the various technical organizations functioning particularly in the oil-producing and refining areas. In the list of subjects proposed for the fall meetings is the problem of estimating petroleum reserves. Various factors requiring study will include productive sand volume, porosity, average permeability, saturation, and types of recovery. Research papers are proposed dealing with energy consumption per unit of oil recovered, reservoir pressure or energy loss relationship to the usual volumetric method of estimation, and the study of oil and gas segregation within the reservoir. Other subjects tentatively suggested include new casing practice in relationship to wells producing from several productive zones, progress in lifting methods, repressuring, advanced methods in drilling economies, and the economics of conservation. Although the threat of overproduction yet remains, to a lesser degree than during the past few years, intensive activity is now being directed towards the discovery of new petroleum reserves. This situation undoubtedly will influence, in some considerable degree, the channels through which technical activities will be directed. A continuation of the commendable work on production statistics for the various oil-producing states and foreign countries has been effected. The usual papers dealing with the general economics of the industry will be reserved for the annual New York Meeting. The Stabilization Committee maintains its membership of nationwide authorities, and interest is manifest in new developments to meet the changing requirements of the industry.

Jan 1, 1935

By Bjorn Bolviken

Bjorn Bolviken (Geochemist, Geological Survey of Norway, Trondheim, Norway)-Under the heading "Recognition of Anomalies," the author states, "If the frequency distribution is actually log-normal, the probability of these high values being part of the background population is small (less than 0.023 and 0.0013 for 2 and 3 standard deviation, respectively)." The figures quoted seem to be the probabilities of these high values being the mean rather than part of the background population unless "background" is defined as one single concentration. If the background is considered to be a statistical distribution of concentrations,50 (which is probably the case here since the author uses the term "background population"), the probability of any observed value being part of the background may be estimated through a calculation of the number of observed values that are in excess of (or below) the number expected to belong to the background. Apparently, some confusion exists in the literature regarding this point. Many authors accept the concept of background as being a statistical distribution, but do not seem to recognize the consequences of this concept. One of these consequences would be that the background of a chemical element should comprise any concentration between zero and a theoretical maximum, which is governed by the chemistry and mineralogy of the material

Jan 1, 1974

By R. S. Dean

MANY studies have been made of the properties of steel produced by adding varying amounts of sponge iron to the charges used in steel-making furnaces.1-3 The results of these previous studies, however, have failed to disclose a reason for the belief of steelmakers that steel made in this way is definitely different from steel made entirely from scrap or iron melting stock. This paper deals chiefly with the structure of the sponge iron, of the wrought iron made by welding the sponge iron into blooms, and of the steel made by melting the forged and rolled blooms. It is believed that the structure of the final steel is inherited from the ore and that this inherited structure produces marked differences in the properties of the steel and explains the feeling of steelmakers which is based on their experience. Three kinds of sponge iron were used in this investigation: One made from a limonite ore reduced with natural gas, one made from a hematite ore reduced with natural gas, and one made from a magnetite ore reduced with charcoal. The sponge iron made by reduction with natural gas

Jan 1, 1935

By Phillip E. Butler

The Pennsylvania Dept. of Transportation is actively engaged in the utilization of coal mine refuse in the construction of highway embankments. Long-held objections for utilization are invalidated by research, laboratory data, and construction performance. Laboratory, engineering, construction, and environmental impact analyses are presented from the construction of the Cross Valley Expressway embankment at Forty Fort, Luzerne County, Pa. Comparisons of laboratory data and construction measurements are given. The refuse embankment is the first of its size in Pennsylvania, and possibly the U. S., covering 1.5 million cu yd.

Jan 1, 1977

By Robert McKay

THE practical study of corrosion requires consideration off its economic aspects. It must be based on sound scientific principles, but it should be borne in mind that probably the most important object of a corrosion test is to determine what metal in corrosion-resisting construction will produce the greatest operating profit. Thus the corrosion test must be directly connected with money values or it is not a practical corrosion test. This, perhaps unusual, connection between corrosion and economics is partially due to the fact that corrosion deals only with the time factor or duration of equipment, and it is almost the only test which deals with this feature. In these statements a departure is made from the academic definition of the word corrosion and it is done deliberately. The use of the term corrosion is unusual. It is as though we spoke of a tensile test as. a "breaking" test. We are not interested primarily in the break but in the strength of the metal. There is no English word which expresses our main interest in corrosion-testing, but let us have clearly in mind that we make corrosion tests to prevent corrosion. Our real interest is in this corrosion-prevention, not in the corrosion. Previous to 1922, it was common comment that "it is impossible to determine the course of corrosion by laboratory testing." This statement was true at that time in that the technique of laboratory testing for corrosion resistance was so vague that tests in the laboratory gave untrue results almost as often as true ones. This was so, even in the simple case of determining which one of two metals better resists a given solution. While this is no longer true the number of misleading "corrosion tests" still being ground out by laboratories is too large in the light of our present knowledge. There are two important features of corrosion testing whose neglect is a large contributing factor to misleading results: (1) The economic relations of the corrosion tests to other tests; (2) testing technique.

Jan 1, 1929

By S. M. Matthews, D. J. Maconochie, L. G. Alexander, V. H. Tillmann

Case studies of the behaviour of large open stopes at the New Broken Hill Consolidated Mine, Broken Hill and the CSA Mine, Cobar, N.S.W. are considered. Deformations were measured by multipoint rod extensometers in sufficient detail to note the phases of rock behaviour, from intact through to rock-fall. In one case readings were obtained from a zone of stress failure in which two bumps, felt as ground tremors, occurred. In this case noise and stress were also monitored. Deformations were analysed in relation to previously measured in situ rock stress, and conclusions drawn about the degree of conformity to, and the areas of departure from, elastic model behaviour. Attempts to describe the growth of instability utilize reduction factors of the apparent modulus, a magnification factor for the apparent Poisson's ratio, and a correlation between progressive noise count and displacement. Monitoring itself is seen as an aid in determiing the final dimensions of stopes and pillars. One large stope, of intermediate dimension 80 m, was mined essentially without change of plan, whereas a change in mining plan was necessary in other stopes. Aspects of interest to mine planners, and areas where futher research is needed, are indicated.

Jan 1, 1981

By A. L. Fentress, P. R. Bucky

The purpose of this paper is to present a scientific method for determining the proper span and shape of roof for safe and economical mining; at present, these two vital factors wherever pillars are left to support the roof are determined by local practice or general experience. To develop the method described here, experimental laboratory work was done. The arch adopted was a segment of a circle, a flat roof being considered an arch with an infinite radius. Hitherto, arches have been used underground without the background of stress analysis that generally precedes arch construction on the surface. In many cases results have not been as expected, because of the lack of knowledge of the factors affecting its strength and behavior. A theoretical and experimental study of arches should furnish information that will make it possible to design safe and economical surface structures as well as underground openings. For example, on the subject of mine drifts and tunnels, the present idea is that arching their backs increases their strength; this paper will indicate that this is not always true, and if it can be shown that under certain conditions arching becomes unnecessary an economic saving will result. In room-and-pillar work a question may arise as to whether arching the roof and gobbing the excavated material will result in timber saving, and a decrease in the dangers from falls of roof. It is to be distinctly understood that each mine must be treated as an individual problem, and that answers to these questions and many others can now be found after experimental laboratory data have been obtained. Mine-Arch Structure Fig. 1 shows the elements that affect the strength or behavior of the experimental arch. They are the span, crown thickness, radius of curvature, rise and restraint. The restraint in all cases was made sufficient to cause the arch to fail without displacing the restraining sides. Fig. 2a is a photograph of a model arch prepared for testing in the centri-

Jan 1, 1934

By H. G. Moulton

H G. MOULTON should not be confused with the famous economist of the same name. Our H. G. stands for Herbert George, whereas the chief of the Brookings Institution is Harold Glenn. Like most so- called New York members of the Institute's hoard, Mr. Moulton came from the West, in this case from Idaho where he was born, and Oregon, where he was educated at the University of Oregon. His early work included such jobs as mucker, assayer, smelter, chemist, mine surveyor, draftsman, engineer on surveys and construction, and assistant on mine examinations. In 1909 he was engaged as mining engineer by the firm of Eugene Meyer, Jr. S' Co., continuing with them for the next eight years.

Jan 1, 1937

By Jay R. Burns

Two magnesium sand-casting alloys are commonly favored in the United States. These are referred to as H and C alloys (Dow Chemical Co.) or AM265 and AM260 alloys (American Magnesium Corporation). Both are of an aluminum-zinc-manganese type. H alloy contains 6 per cent aluminum and 3 per cent zinc and is characterized by relatively good toughness. C alloy contains g per cent aluminum and 2 per cent zinc and is employed where high yield strength and pressure tightness are required. Examination of magnesium castings poured in Europe and England,1,2 however, demonstrates that H and C alloys are replaced by A8 and AZ91, respectively. That is, A8 represents a magnesium alloy having superior toughness while AZ91 is suitable for high yield strength and pressure-tight applications. The basic difference between the American and European alloys is that the foreign alloys employ a somewhat higher aluminum content and less zinc than is found in H and C alloys. The mechanical properties of the alloys, when divided into high and low-aluminum groups, are quite similar, as determined from separately cast foundry-control type test bars.3 In this paper the decrease of mechanical properties caused by any given amount of microporosity is measured for H, C, A8, and AZ91 alloys. The relative susceptibility of each of the four alloys to microporosity is also determined. Typical mechanical properties and nominal chemical analyses are reported in Table I. [ ] The apparent similarities between the two alloys in each group have led to considerable discussion as to the relative merits of each of the compositions.2 Popular points for comparison between the alloys have been the relative susceptibility of each of the four alloys to microporosity5 and the effect of this microporosity on their mechanical properties. It is primarily intended, in this paper, to show the

Jan 1, 1946

By F. P. Donohue

The observations and data presented in this paper are the result of extensive study of flowing wells, most of which were in the Maracaibo Lake Basin of Venezuela. The Lago Petroleum Corpn. had extensive production in this area, gas-oil ratios were low, and the problem was to determine whether by careful handling of the wells with respect to flowing conditions and by conserving the gas, the oil production of the wells could be maintained by natural flow until it had declined to a rate which could be handled with an ordinary working barrel, thereby avoiding the high cost of gas-lift equipment installation in the lake bed. The problem was complicated by the nature of the wells themselves. Production is from soft, comparatively unconsolidated sands, necessitating screen pipe in all wells. It was not only necessary to keep the wells flowing but to keep them flowing without heading, as the release of pressure upon making a head brought large quantities of sand into the wells, sanding them up or possibly cutting out the screen pipe. In furtherance of the plan of keeping wells flowing as long as possible, each well was equipped with a casinghead and tubinghead recording pressure gage, and an oil and gas separator set. About one-half of the wells were equipped with gas meters. All wells were tubed before bringing into production. Frequently individual gages were taken on each well. A large scale chart was plotted for each well, showing daily oil production, gas production, gas-oil ratio, tubinghead pressure and casinghead pressure. Any deviation from the normal was immediately checked and the condition remedied if possible. Theory of Flowing Wells Based upon considerable study of these records, it is believed that the flow of a well actuated by gas is mainly a problem in velocity, a certain minimum velocity in the flow string being necessary for the gas to carry the oil. If this minimum velocity is not obtained the oil drops back and the well heads or goes dead. The point of minimum velocity is of course at the bottom of the tubing, where the gas is under the highest pressure and therefore occupies the least volume. Some years ago when the success of the gas-lift at Seminole was so pronounced, there was considerable broadcasting of the statement that

Jan 1, 1930

By Alan T. Gorton, T. L. Joseph, Gust Bitsianes

High-temperature X-ray diffraction techniques were used to determine thermal expansion coefficients of iron and its oxides. Lattice parameters of a and iron, wiistite, magnetite, hematite, and goethite were determined and plotted as a function of temperature. From these results, the true and mean linear thermal expansion coefficients were calculated. In the case of noncubic crystals, the expansion coefficients were determined along each of the crystallographic axes. The effect of the magnetic transformation on lattice parameter was measured for a iron and magnetite at their respective curie temperatures. COEFFICIENTS of expansion for iron and its oxides were determined from the temperature dependence of their lattice parameters. From these data, the true linear coefficients were derived by means of the formula: at =[(l/ao )(dao/dt)] [1] where at is the true linear coefficient of expansion, a, is the lattice parameter in angstrom units, and all variables are referred to the temperature, t, in OC. Thus the true expansion coefficient represents the instantaneous change in lattice parameter on a unit basis and at a particular temperature. A second expansion coefficient is also often used. It is termed the mean linear coefficient and is defined in the following way: am = [ao(t) - ao(O)]/ao(0) l [21 This coefficient represents the average change in lattice parameter on a unit basis but at a specified parameter length, ao at O°C, and over a specified temperature range,1 to 0°C. Generally the true co-

Jan 1, 1965

THE second operation in the art of casting, and one of the greatest importance, is that of melting and thoroughly liquefying the materials of which you wish to make your casting. On this operation depends the whole outcome of your intentions and the perfection of your work. Without it, even though you had a great abundance of moulds and vast quantities of bronze, your desires, labor, and expense would all be in vain. In this operation I find on consideration that, in addition to experience, there are three necessities-perhaps indeed four-that must be provided without fail. The first is the furnace or other agent which contains the fire and the metal brought together. The second is the wood or charcoal which is the necessary and proper nutriment of the fire, from whose virtues are derived the greater or lesser forces which, according to their kind, are ready to effect what is required. The third is to have the materials disposed to easy fusion by means of corruption, alloying, or by their own nature. The fourth, as the motivating cause of the whole, could perhaps be listed as the first-this is the ingenuity and good judgment of the worker, together with the bodily exertions not only of himself but also of his helpers in addition. For, besides a certain ordinary caution, it is necessary to pay particular attention, first, to see that the furnaces, machines, ladles, hearths, refineries, and other kinds of instruments or similar vessels be made so as to dispose the metals for melting, and, when melted, that they easily maintain them so. These should also be prepared in such a way that they cannot be injured by the fire, for if they should be damaged the operation would fail. In order to do this, it is first necessary that you arrange the instruments with forethought and action so that the power of the fire can operate. Fire operates on things only when brought together with them in long-continued operation, or when driven by a great force of wind. It burns many things and softens others, but it makes the metals as liquid as water.

Jan 1, 1942

By C. C. Nathan

Data are resented on the physical properties of five waxes obtained from fields in Texas and Louisiana in which "parafin" troubles are being experienced. The crude parafin was fractionated into three components, voluble in cold acetone, soluble in boiling acetone, and insoluble in boiling acetone. The acetone insoluble fraction was found to consist essentially of straight chain parafin hydrocarbons in the molecular weight range 525 to 700. Solubilities of the purified high molecular weight parafins were determined in a number of solvents. It was found that in hydrocarbon solvents, including crude oil, solubilities could be calculated satisfactorily by use of ideal solubility relations. In chlorinated, and oxygenated solvents, large deviations from ideal behavior were observed. These deviations could be partially correlated with the internal pressure of the solvent. INTRODUCTION A problem encountered in many producing oil fields is that of "paraffin" deposition. The problem refers to the deposition of material from the crude oil onto tubing, pumping rods, flow lines, or other material contacted by the crude. This problem has been recognized for nearly a hundred years, and numerous investigations have been reported on its causes and prevention or alleviation. One of the more comprehensive of such investigations was published by Reistle1 in 1932. A few of the salient findings of his report are briefly as follows: The term "paraffin" as used to describe this problem refers to the deposit of carbonaceous material which is not soluble or dispersible by the crude oil under the conditions where deposition occurs. The "paraffin" normally consists of high molecular weight paraffin hydrocarbons, both straight chain and branched, resins and asphaltic materials of undetermined nature, occluded oil and water, and possibly sand. In consistency, the deposit may vary from a soft, sticky material, to one which is hard and brittle. Deposits are usually black, although lighter colors are sometimes observed. Under the conditions of temperature, pressure, and crude oil composition occurring in the underground reservoir, the paraffin is in suspension or solution in the crude. As the oil flows to the surface, there is generally a reduction of temperature, pressure, and the amount of dissolved gases contained in the oil. Reduction of temperature and gas break-out were shown by Reistle to be factors causing reduced solubility of the paraffin in the crude. Thus, as the crude containing paraffin rises to the surface and flows to storage tanks at atmospheric temperature, the solubility of the paraffin may be exceeded. Deposition will begin at the point in the system where the temperature of the system falls below its cloud point, and continue as long as there is a further drop in the solution power of the crude for the paraffin. The severity of the deposition as well as the location of the bulk of the deposition, i.e., in subsurface or surface equipment, will depend on the amount of paraffin originally in the crude, the manner in which pressure and temperature of the crude

Jan 1, 1956

By R. Al-Hussainy, H. J. Ramey

Previous gas well test analyses have been based mainly upon linearizations of ideal gas flow results, although a method for drawdown analysis based upon real gas flow results has been proposed. Linearizations based upon ideal gas flow require estimation of gas physical properties at Tome sort of average pressure, and implicitly involve the assumption that pressure gradients are small everywhere in the reservoir. A new real gas flow equation has been developed by means of a substitution which couples presTure, viscosity and gas law deviation factor. This sub-stitution has been called the real gas pseudo-pressure. Use of the real gas pseudo-pressure leads to simple equations describing real gas flow which do not contain pressure-dependent gas properties, and which do not require the assumption of small pressure gradients everywhere in the flow system. Equations required to determine flow capacity, well condition and static formation pressure from pressure drawdown and build-up tests with the real gas pseudo-pressure concept are presented. Also shown are applications of the real gas pseudo-pressure to back-pressure testing, the gas materials balance and rigorous determination of average gas properties for previous gas flow equations. Included are sample calculations for well test analyses. INTRODUCTION A recent study' of the flow of the transient flow of real gases in ideal radial systems showed that it is possible to consider gas physical property dependence upon pressure by means of a substitution called the real gas pseudo-pressure. The substitution has the advantage that it enables engineering solutions for steady and transient flow of real gases that are more accurate and general than those previously available. The solutions are particularly important for the case of gas flow in tight, high-pressure formations under large drawdowns. Even for more ideal flow conditions, the real gas pseudo-pressure concept leads to important rules for finding average gas physical properties pertinent for older well test analyses. Ref. I provides a detailed study of the theory behind the real gas flow correlations to be used in this paper. The purpose of this paper is to provide necessary engineering forms for use of the real gas flow results, and to illustrate applications. The following considers flow of real gases in an ideal radial flow system. It is assumed that: (1) formation thickness, porosity, water saturation, absolute permeability, temperature and gas composition are constant; (2) gas compressibility and density are functions of pressure as described by the gas law pv = znRT; (3) gas viscosrty is a function of pressure; (4) effective permeability to gas may be a function of pressure to account for liquid condensation; (5) condensate is immobile; and (6) the formation has no dip.

Jan 1, 1967

By John Gross

THE deductions drawn in crushing and grinding operations have heretofore been based on a separation of the products into various sizes. A crushed product may be sized by sieving, by elutriation, and by aid of the microscope. To estimate the surface of each size the relation of the surface to the estimated average diameter must be assumed. Such a relation, owing to the irregularity of the particles, may involve two assumptions: First, a factor to convert average diameter to surface for one particular size; and second, a variation in the factor as the diameter of the particle changes. Obviously a surface measurement in which such assumptions and estimates are involved is questionable. In the first paper of this series1 a method has been given by which an accurate measure of surface of quartz can be obtained from its dissolution rate. By the use of this method, surface measurements have been made on a series of sieve sizes of crushed quartz, the results of which are given and discussed in this paper.

Jan 1, 1928

By R. T. DeHoff

Saltykov's meihod for the determination of the size distribution of spherical particles from measurements made on random plane sections is extended to particle shapes which are not equiaxed. The analysis permits the deterrrzination of the size distribution of aggregates of ellipsoidol particles provided all particles have tlze same shape. V ARIOUS solutions to the problem of the determination of the size distribution of spherical particles from measurements made on random plane sections have appeared in the literature since the original solution was first published by Scheill in 1934. Solutions have been offered utilizing measurements of the diameter1y2 or area3'4 of circular sections that result when a test plane is passed through an aggregate of spherical particles, and the length of intercept5y6 that results when a test line is passed through the aggregate. To the best of the knowledge of the author, no method has been proposed which permits the determination of the size distribution of particles that are not equiaxed. The purpose of this paper is to develop a method which permits the determination of the size distribution for a specific class of particle shapes which cover awide range of axial ratios; namely, ellipsoids of revolution. In the interests of simplicity, it is necessary to limit consideration to aggregates of particles which are all similar in shape; that is, the ellipses which, by rotation about one of their axes, generate the particles, all have the same axial ratio. The size distribution, which is to be determined by the analysis, is arbitrary. It is also assumed that the section, or sections, upon which the measurements are made represent the average of all possible sections through the structure. This ideal condition can be approached as nearly as may be desired by observing a sufficient area of sections taken at random positions in a randomly oriented aggregate, and in random positions and orientations in an aggregate that has one or more axes of orientation. SIZE DISTRIBUTION FOR PROLATE ELLIPSOIDS Consider an aggregate of cigar shaped, geometrically similar particles (prolate ellipsoids), dispersed in an opaque matrix. Let the size of each particle be specified by the length of its minor axis, By Fig. 1, and the shape, q, be defined by the ratio of its minor to its major axis, B/A. Let the index, j, refer to dimensions of ellipsoids in a particular size class, and the index, i, to dimensions of an ellipse resulting from the intersection of a test plane and a particle. The size of such a section is specified by the length of its minor axis, b. Let the particles be arbitrarily divided into k size classes, and let the increment of size between each class be A, where A = &,$, B,,,being the minor axis of the ellipsoids in the largest size class. Since all sections are represented on the test plane, the minor axis of the largest of the sections observed, results from the intersection of the test plane with an ellipsoid in the largest size class at its center, and is therefore equal to Bmax Thus the increment, A = The final result will consist of the k numbers which represent the number of particles in each size class per unit volume of aggregate:

Jan 1, 1962